Carbene complexes of iron, molybdenum, and ruthenium: a new route to metal–carbene derivatives

Abstract

The acyl derivatives M–Ac, where M =(π-C₅H₅)Fe(CO)P(Hex)₃, (π-C₅H₅)Mo(CO)₂P(Hex)₃, (π-C₅H₅)Ru(CO)₂(π-C₅H₅)Ru(CO)PPh₃, or (π-C₅H₅)Ru(CO)P(Hex)₃ have been prepared. Treatment of these with acids H⁺A^– A = Cl or BF₄, or with trialkyloxonium salts, R₃O⁺BF₄^–, R = Me or Et, forms salts of the corresponding carbene derivatives, [M = C(OR′)Me]⁺ A^–, R′= H or alkyl. The hydroxy-carbenes react with diazomethane forming the methyl analogues, R′= Me. Treatment of the carbene [(π-C₅H₅)Fe(CO)(PPh₃){C(OEt)Me}]⁺BF₄^– with sodium borohydride forms the π-ethoxyethyl derivative (π-C₅H₅)Fe(CO)(PPh₃){CH(OEt)Me}, and with lithium methyl, propane, propene and the acyl derivative, (π-C₅H₅)Fe(CO)(PPh₃)(Ac) are formed.